The Collaborative International Dictionary of English v.0.48:

Gavelkind \Gav"el*kind`\, n. [OE. gavelkynde, gavelkende. See
   Gavel tribute, and Kind, n.] (O. Eng. Law)
   A tenure by which land descended from the father to all his
   sons in equal portions, and the land of a brother, dying
   without issue, descended equally to his brothers. It still
   prevails in the county of Kent. --Cowell.
   [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

GAVELKIND. Given to all the kindred, or the hold or tenure of a family, not
the kind of tenure. Eng. law. A tenure or custom annexed or belonging to
land in Kent, by which the lands of the father are equally divided among all
his sons, or the land of the brother among all his brothers, if he have no
issue of his own. Litt. s. 210.